Problem: $ { \left[\begin{array}{rr}{2} & {4} \\ {4} & {-1} \\ {2} & {-1}\end{array}\right]+\left[\begin{array}{rr}{-1} & {1} \\ {-1} & {3} \\ {2} & {0}\end{array}\right] = {?} } $
Answer: To find the sum of two matrices, add the corresponding items between each matrix. ${\left[\begin{array}{rr}{2}+{-1} & {4}+{1} \\ {4}+{-1} & {-1}+{3} \\ {2}+{2} & {-1}+{0}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{1} & {5} \\ {3} & {2} \\ {4} & {-1}\end{array}\right]}$